CVE-2026-91973

Published: Sep 15, 2026Modified: Sep 16, 2026Deferred

8.7

Vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XShow less

Source: disclosure@vulncheck.com (Secondary)

Description

Vikunja before 2.6.0 contains an authentication bypass vulnerability in CalDAV BasicAuth endpoints that lack rate limiting protection. Remote unauthenticated attackers can issue unbounded credential-guessing requests against /dav, /.well-known, and /feeds routes to bypass the instance's anti-brute-force controls and compromise password-only accounts.

Related CWEs

CWE-307

Improper Restriction of Excessive Authentication Attempts

The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame, making it more susceptible to brute force attacks.

References (3)

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-m469-88xx-8rx2

Source: disclosure@vulncheck.com

https://www.vulncheck.com/advisories/vikunja-before-2.6.0-authentication-bypass-via-caldav-basicauth

Source: disclosure@vulncheck.com

https://github.com/go-vikunja/vikunja/security/advisories/GHSA-m469-88xx-8rx2

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Timeline

No history available yet.